• Korean Journal of Applied Biomechanics
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• v.24 no.3
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• pp.229-238
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• 2014

This study comparatively analyzed the speed and segment coordination characteristics of Taekwondo hand techniques, while different attention focusing strategies were utilized. Ten elite Taekwondo poomsae athletes participated, and three different strategies (no focus, target focus, body focus) were utilized in random order. The hand velocity and upper body segment coordination characteristics were analyzed, with the following results. First, the maximum magnitudes of the hand velocity differed between the focus conditions for the Araenaereomakgi and Momtongjireugi techniques. Second, the angular velocity and kinetic energy transfer patterns of the segments differed between the focus conditions, and in the case of the body focus condition, the movement was more correct according to the theory. Third, the shoulder and elbow joint coordination patterns differed between the focus conditions, with more efficient movement shown with the body focus condition. In conclusion, we confirmed the potential of effectively using an attention focusing strategy in a taekwondo teaching situation. However, the effect on the movement coordination and results of the movement could be changed by a difference in the cue provided or the type of the task. In addition, depending on the task, the attention focusing strategy could affect the efficiency of the movement. Therefore, coaches and masters of Taekwondo will have to constitute determine the appropriate attention focusing cues based on the task.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.11
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• pp.1824-1835
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• 2010

This study develops tight-fitting torso patterns for performance garments by taking into account the skin deformation generated directly from a 3D scan during arm movements. The skin deformation caused during the arm movements was scanned after scanning the skin surface stamped with a circle. To create a torso pattern in response to skin deformation, the ratio and direction of the skin deformation were first measured and analyzed so that the 3D human body could be segmented. After translating, the 3D skin surface was segmented into 2D flat patterns, designing nude patterns and reducing them as well as tight-fitting shirts: the skin deformation segment shirts were made in response to the skin deformation. The features of the fabric deformation and the garment pressure were analyzed and evaluated. In comparison with a clothing construction segment shirt, the diameter of the skin deformation segment shirt was smaller as well the ratios of extension and reduction was less. The garment pressure of the skin deformation segment shirt was higher. The skin deformation segment shirt fitted more tightly compared to a clothing construction segment shirt as it covered the body more thoroughly and was as comfortable as the other shirts with less fabric deformation made as the body moved.

• Journal of Korean Foot and Ankle Society
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• v.19 no.4
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• pp.161-164
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• 2015

Purpose: The purpose of this study is to define the geographic patterns of partial avascular necrosis (AVN) of the talar body and to determine whether there were any predictors of both the location and occurrence of partial AVN. Materials and Methods: Nineteen patients with fracture of the talar neck treated by open reduction and internal fixation and followed up for more than 1 year were analyzed. The radiographs were examined 6 to 8 weeks after the operation for Hawkins sign and if it was not observed, magnetic resonance scans were performed. The three-dimensional analysis was performed using Mimics 17.0 (Materialise). The incidence of collapse and time to operative intervention was recorded. Results: Partial AVN of the talar body was observed in six out of 19 patients. The avascular segment of the talar body was located predominantly in the anterolateral portion. The average volume of the avascular segment was $289mm^3$, and it occupied 1% of total volume of the talus, and 10% of the talar dome. Collapse occurred in one patient in the area of the avascular process. There were no observable trends with regard to Hawkins classification, incidence of collapse, or time to operative intervention to the location of the avascular segment. Conclusion: Partial AVN can occur after fracture of the talar neck. The predominant location of the avascular segment was the anterolateral portion of the talar body. This information may be helpful to understanding the process of avascular necrosis of the talar body.

• Journal of Korean Neurosurgical Society
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• v.42 no.4
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• pp.265-270
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• 2007

Objective : The current literature implies that the use of short-segment pedicle screw fixation for spinal fractures is dangerous and inappropriate because of its high failure rate, but favorable results have been reported. The purpose of this study is to report the short term results of thoracolumbar burst and compression fractures treated with short-segment pedicle instrumentation. Methods : A retrospective review of all surgically managed thoracolumbar fractures during six years were performed. The 19 surgically managed patients were instrumented by the short-segment technique. Patients' charts, operation notes, preoperative and postoperative radiographs (sagittal index, sagittal plane kyphosis, anterior body compression, vertebral kyphosis, regional kyphosis), computed tomography scans, neurological findings (Frankel functional classification), and follow-up records up to 12-month follow-up were reviewed. Results : No patients showed an increase in neurological deficit. A statistically significant difference existed between the patients preoperative, postoperative and follow-up sagittal index, sagittal plane kyphosis, anterior body compression, vertebral kyphosis and regional kyphosis. One screw pullout resulted in kyphotic angulation, one screw was misplaced and one patient suffered angulation of the proximal segment on follow-up, but these findings were not related to the radiographic findings. Significant bending of screws or hardware breakage were not encountered. Conclusion : Although long term follow-up evaluation needs to verified, the short term follow-up results suggest a favorable outcome for short-segment instrumentation. When applied to patients with isolated spinal fractures who were cooperative with 3-4 months of spinal bracing, short-segment pedicle screw fixation using the posterior approach seems to provide satisfactory result.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.45-61
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• 2005

Stance is defined as any state in which the total mass of the body is supported by the feet. In order to maintain stance, the sum of gravito-inertial forces acting on the body must be registered by equal and opposite forces at the region of contact between the organism and the support surface. Balance is controlled by applying forces to the surface of support so as to maintain the body's center of mass vertically above the feet. for a muIti-segment organism, there can be a variety of ways in which balance can be controlled, since movements of different body segments can have similar effects on the control of balance. In general, the organism tends to have a body configuration that is aligned with gravito-inertial force when there are no external forces acting on it. If any segments of the body are not aligned with gravito-inertial force vector, a torque on that segment would tend to move the body's center of mass. The maintenance of postural stability is accomplished in humans by a complex neural control system. This requires organizing integrating and acting upon visual, vestibular, and somatosensory input, providing orientation information to the postural control system. The information necessary to control and coordinate movement is provided by the visual sense of eye position with respect to the surrounding surface layout, the vestibular sense of head orientation in the gravito-inertial space, and the somatic sense of body segment position relative to one another and to the support surface. In this study, perception and action capability was examined from various points of view. The underlying assumption of the study was that the change of postural configuration could be effected by organism, environment and task goal.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.117-121
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• 2023

Research on walking assistance exoskeletons that provide optimized torque to individuals has been conducted steadily, and these studies aim to help users feel stable when walking and get help that suits their intentions. Because exoskeleton auxiliary efficiency evaluation is based on metabolic cost savings, experiments on real people are needed to evaluate continuously evolving control algorithms. However, experiments with real people always require risks and high costs. Therefore, in this study, we intend to actively utilize human musculoskeletal simulation. First, to improve the accuracy of musculoskeletal models, we propose a body segment mass distribution algorithm using body composition analysis data that reflects body characteristics. Secondly, the efficiency of most exoskeleton torque control algorithms is evaluated as the reduction rate of Metabolic Cost. In this study, we assume that the torque minimizing the Metabolic Cost is the optimal torque and propose a method for obtaining the torque.

• Journal of Sensor Science and Technology
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• v.31 no.3
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• pp.156-162
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• 2022

This study estimates the relative position between body segments using segment orientation and segment-to-joint center (S2J) vectors. In many wearable motion tracking technologies, the S2J vector is treated as a constant based on the assumption that rigid body segments are connected by a mechanical ball joint. However, human body segments are deformable non-rigid bodies, and they are connected via ligaments and tendons; therefore, the S2J vector should be determined as a time-varying vector, instead of a constant. In this regard, our previous study (2021) proposed a method for determining the time-varying S2J vector from the learning dataset using a regression method. Because that method uses a deformation-related variable to consider the deformation of S2J vectors, the optimal variable must be determined in terms of estimation accuracy by motion and segment. In this study, we investigated the effects of deformation-related variables on the estimation accuracy of the relative position. The experimental results showed that the estimation accuracy was the highest when the flexion and adduction angles of the shoulder and the flexion angles of the shoulder and elbow were selected as deformation-related variables for the sternum-to-upper arm and upper arm-to-forearm, respectively. Furthermore, the case with multiple deformation-related variables was superior by an average of 2.19 mm compared to the case with a single variable.

• Journal of Korean Neurosurgical Society
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• v.52 no.4
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• pp.384-390
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• 2012

Objective : The objective of this study was to investigate the morphologic characteristics between the vertebral body and the regions of the cervical and thoracic spinal cords where each rootlets branch out. Methods : Sixteen adult cadavers (12 males and 4 females) with a mean age of 57.9 (range of 33 to 70 years old) were used in this study. The anatomical relationship between the exit points of the nerve roots from the posterior root entry zone at each spinal cord segment and their corresponding relevant vertebral bodies were also analyzed. Results : Vertical span of the posterior root entry zone between the upper and lower rootlet originating from each spinal segment ranged from 10-12 mm. The lengths of the rootlets from their point of origin at the spinal cord to their entrance into the intervertebral foramen were 5.9 mm at the third cervical nerve root and increased to 14.5 mm at the eighth cervical nerve root. At the lower segments of the nerve roots (T3 to T12), the posterior root entry zone of the relevant nerve roots had a corresponding anatomical relationship with the vertebral body that is two segments above. The posterior root entry zones of the sixth (94%) and seventh (81%) cervical nerve roots were located at a vertebral body a segment above from relevant segment. Conclusion : Through these investigations, a more accurate diagnosis, the establishment of a better therapeutic plan, and a decrease in surgical complications can be expected when pathologic lesions occur in the spinal cord or vertebral body.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.205-215
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• 2020

Objective: The purpose of this study was to investigate the relative angles and cross-correlation between body segments and ski among four alpine ski turning techniques. Method: 19 alpine ski instructors participated in this study. Each skier asked to perform 4- types of turning technique, classified by radius and level. 8 inertial measurement units were used to measure orientation angle of segment and ski on the anteroposterior and vertical axis. Results: Significant differences were found between types of turning in the segments-ski relative angle on the anteroposterior and vertical axis (p<.05). Although, cross-correlation showed a high correlation between angles of segment and ski, there were significant differences between types of turning. Conclusion: Based on our results, the relative movement and timing between each segment and ski is different according to the turning techniques, so the training methods should be applied differently.

• Journal of Veterinary Clinics
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• v.7 no.1
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• pp.371-380
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• 1990

This experiment was performed to investigate the electrocardiographic changes in experimentally induced hypocalcemia and hypercalcemia in Korean black goats by dosing with 5% disodiumethylene diamine tetraacetic acid at 0.07$m\ell$/kg body weight/min and 10% Ca-borog-luconate at 0.075 $m\ell$/kg body weight/min, respectively. the result were summarized as follows： Heart rate, S-T segment and Q-Tc interval at 3.23 ${\pm}$ 0.10mEq/L plasma calcium level(hypocalcemia) were increased to 100${\pm}$10.5 rate/min, 132 ${\pm}$10msec and 510${\pm}$40msec, respectively. Heart rate, S-T segment and Q-T interval at 6.89${\pm}$0.23mEq/L plasma calcium level(hypercalcemia) were decreased to 73.2${\pm}$5.16 rate/min, 87${\pm}$10msec and 372${\pm}$30msec, respectively. The degree of changes of the heart rate, S-T segment and Q-Tc interval at low plasma calcium level was higher than those at high plasma calcium level.